Quantum communication is the science of transmitting quantum states from one place to another. This field has received significant attention over the past few years due to the discovery of quantum cryptography.

Quantum cryptography exploits a unique property of single particles, like photons, making them exist in two separate states. Once you measure the state of a particle, you can instantly change its state, meaning photons would be able to be passed between two parties safely. Scientists have described quantum cryptography as a way of creating “unbreakable” messages, making it a viable tool for technology companies, governments, banks and other security-focused clients.

The transmission of encryption keys over long distances remains a significant challenge for scientists, but the intensity of signals tend to weaken as they travel further, because photons can get absorbed or scattered off molecules.

Jennewein and Higgins lead one of several teams around the world trying to pursue the concept of a quantum satellite. A satellite 22,000 miles above the Earth would be able to act like a relay between two ground stations in a way that allows them to establish a secure connection by sharing an encryption key made of photons.

They have been studying the overall design features of the satellite and ground stations, and have emphasized the need for them to be precisely aligned so they can be certain that what they measure corresponds to the photons that are prepared.

“With the prospect of global-scale quantum communications and fundamental quantum science within new, unexplored regimes, the next few years are sure to be exciting,” Jennewein and Higgins wrote in the journal Physics World.

Last September, physicists claimed they achieved quantum teleportation over a record distance of 88 miles, creating the first major step towards building satellite-based quantum communication.

During this venture, the team wrote in Nature they transmitted quantum states between the two Canary Islands of La Palma and Tenerife, surpassing the previous record by about 28 miles set by Chinese researchers months before.